AT&T Definity Callmaster I Instruction Manual download pdf (Page 128)

POWER AND GROUNDING

TABLE Q

(continued).

-48 Volt DC Input Power Requirements

Parameter Requirements

Redundancy Redundancy of the battery chargers/rectifiers should be considered.

This would also provide the additional current necessary to recharge

the batteries after being fully discharged.

Electrical Noise Voice band noise from the battery plant to the system must be less

than 32dBmC.

Grounding A single point ground must be maintained.

A ground conductor must be installed from the isolated Ground

Discharge Bar* to the closest Approved Ground via the shortest

route as required by the NEC/REC. The gauge must be no smaller

than the largest conductor in the system and larger than 6 AWG.

The Ground Discharge Bar shall not be connected electrically to the

chassis of the battery plant chargers, power board, or inverter(s).

All output power shall be isolated from the input power.

Lightning Protection There must be adequate lightning protection in the battery plant to

ensure that the system will not be damaged.

As shown in Figure 21, the size of the wire required for the -48 V DC and -48 V return must be

engineered so that

the -48 V DC supplied by the battery plant to the G1 cabinets will be

maintained between -42.5 and -52.5 V DC at all times

to ensure proper operation and to

prevent hardware damage.

* Refer to

DEFINITY



Communications System Generic 1 and Generic 3—Installation and Test

, 555-230-104, for parts

and location information.

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AT&T Definity Callmaster I Instruction Manual Page 128